Determining milling performance of sorghum cultivars by means of abrasive decortication and roller milling techniques

Abstract

Although roller milling has been successfully applied to produce sorghum meal, the South African sorghum milling industry mostly uses abrasive decortication milling. The first objective of this study was to develop a laboratory-scale roller milling technique for a scaled-down roller mil and determine the milling performance of sorghum cultivars, using canonical variate analysis. The second objective was to compare the suitability of abrasive decortication and roller milling techniques to determine milling performance of sorghum. Thirdly, cultivars better suited for roller milling and those, which milled more successfully with abrasive decortication milling, were identified. Grain samples of 24 sorghum cultivars produced during two seasons at three localities were milled with a Tangential Abrasive Dehulling Device and a roller mill consisting of two break rollers with different flute sizes. Canonical variate analysis was found to be a suitable procedure to analyse and predict the roller milling performance. Little variation in milling losses of different cultivars was found with roller milling, while more variation in losses was experienced between cultivars with abrasive decortication. Mean colour was highly acceptable and did not depend on the milling time in the case of roller milling samples. Cultivars PAN 8564, NS 5655, SNK 3337 and SNK 3863 displayed good milling quality when milled using both roller and abrasive decortication milling. Both abrasive decortication and roller milling techniques were found to be suitable for sorghum milling and the determination of milling performance.